The bright spot for Windows 8 in the data from Web analytics company Net Applications: Its share of all Windows PCs increased in March by a larger margin than the month before, reversing a trend of declining growth since the OS launched in October.

According to Net Applications, Windows 8's March usage share -- including what the firm labeled as "touch" for Windows 8 and Windows RT -- was 3.6% of all Windows PCs, up from February's 3%.

Windows 8's share increase in March was six-tenths of a percentage point, larger than February's gain of five-tenths of a point. From November -- the first full month after Windows 8's launch -- through February, the operating system's increases had grown smaller each month.

March was the first time Windows 8's increase was greater than the month prior.

At the same time, however, the gap between Windows 8's and Windows Vista's uptake pace widened.

By the end of its fifth month, Vista powered 4.9% of all Windows PCs, while Windows 8 accounted for 3.6% at the same point in its post-release timeline. The 1.3 percentage point difference between Vista and Windows 8 was the biggest so far in Computerworld's tracking, and twice as large as the gap just two months ago.

Windows 8, of course, is competing in a vastly different world than did Vista, with slumping PC sales prominent, caused in part by a desertion of dollars to tablets, where the operating system -- and its limited-feature sibling, Windows RT -- has yet to make much headway.

Windows 8's ability to run on tablets has not helped the OS. Net Applications' measurement of users running Windows 8 from the "Modern," formerly called "Metro," user interface (UI), increased by just two-hundredths of a percentage point last month, while Windows RT gained one-hundredth of a point. Together, they accounted for just over one-tenth of 1% of all personal computers that went online last month.

In the short-term, there's little chance Windows 8 will match Vista's trajectory: Windows 8 must gain more than 2 percentage points in April to close on Vista, or four times its three-month average increase.

Net Applications also reported on usage shares for older editions of Windows.

The gap between Windows 8's and Windows Vista's uptake clips widened in March to its largest ever. (Data: Net Applications.)